Signaling system



' Feb. 15, 1927.

H. w. O NE ILL SIGNALING SYSTEM 5 Sheets-Sheei2 1 I Filed Dec. 17, 1924Y 1,e17,414 F 15, H. w. O"NE ILL SIGNALING SYSTEM- Fild Ded. 1924 5Sheets-Sheet 2 nyz by A77)? Feb. 1927.

15, w. O'NEILL SIGNALING SYSTEM ts-Shet 3 I Filed Dec. 17,

H. W. ONElLL SIGNALING SYSTEM Feb 15,1927 K 1,611,414

Filed Dec. 1 1924 1 5 sheds-sheet 4 ,hvenfaq: Henry VI. flAeM/ by WWWPatented Feb. 15, 1927. r

"HENRY W. ONEILL, OF ELMHU'RST,

YQBK, nssjrenon no WEST N nnne rn rc ooMrAN INCORPORATED, emu-11w 101m;n.-

A eonronn'r-Ion ionqunw Y-QRK.

swimme s-refinemn nc non filed llecember 17, 192 4 ser anuo. ma ce Thisinvention relates to signaling systems :and more particularly toimproved methods andmeans .for signaling over transmission :lines. i

5 Under the :present telephone practice involving the use of telephonelines interconnecting .difi'erent exchanges, several diflerent methodsof extending connections are employed, such as, manual to manual or inmanual to automatic connections; In a manual to manual connection,thesubscriloer in the originating exchange first secures. a connectionto a toll operators position in his oWn exchange, ,Who then extendsthe'con- 13 nectionover a toll lineto a distant exchange and rings upthetolljoperator as \su chejan exchange. ;The toll operator at this eX-change requests ofthe originating toll op erator, the numberofthefdesired lineand then proceedsto extendthe connection to ,thedesiredsubscriber. In, a, inanuall to. eutomatic connection, thentolloperator in ,the originating exch ange V dials the desired line in theautomatic exchange vvithontth'ejaid Ot'the toll operator at thedistentfexehange. Connections o f these types ina y extend through anumber o fmanual or. automatic exchanges involving the use ofsevereltoll lines. 7 n

It is an object of thisinventionto provide I cord circuit and toll lineequipments suitahlefor use in e tendingieonnections of the above types.3

Anothenobject is to provide, meansassociated with such icord circuit andtoll line equipments, whereby any one of ,thei wel'l known types of toll'llllQS;-n1=2ty,b( employed suches, for example, ordinary wn-e itolllines with or Without repeaters, a channel of a carrier telephoneinstallation, n radio telephone connection, compositewlines orphantom'lines. That is, the'nature of the signals used for performingthe, various functions incidental to the extension of a connection 'issuch that 3 the ,signals may .be' transmitted over any :toll linethesame distanceand at the same eiiiciency as the ordinary voice-modulatedsignals and Without in any Way curtailing t -he. nseii'ulnessorefficiency otthese var-ioustypes, ottoll lines.

Another object ,of, the invention is theprovision of a simplifiedservice observing arrangement--.whereby the service observing operatonmay ;not only ascertain the various types ofconneetions beingestablished over nections. V

the toll \line' but also observe tl ie progress oi establish n o di es ei hillg s c Another object is the provision ofa simtoll l'inej toaccoinplish the :variousisvvitehi lg and supervisory fu c ions F .A comon i l mel t l f e e t; sus f new ,mission oflsignals in eitherdirection over t e t 1 e hd mea s p oi d do t. e

end of the toll lines for automaticnllyiniodns his undam n al equentywith I 't o s le t na ms n nt Oi? qompar tmely l rfiz uen tra m tin thresul n signals ov t l e 11d. jce ii g the ,responding functionjsto befIn the .case' of the swit hing hinctiqns; .i ipu s elere whic a e p edjr d. by interrupting 'thejtu igl ainentali frequency at de is sl Ano hf nn :v th eproyis on, otm an whe eby th vibratoy in ays ffjfih f hbrcircuiting type used combination with a direct 'ciirrenusource iQRtheproduction of frequencies .rnaynbe of the same type for both thefundamental,alternatingcurrents W hin th voice frequen y rai jgetas W lla li thealt na ineeleme sof ,lQwiie eeney an whe by re e ting oils QPIEASfQ i l e a na re edule ing It'h und mentalhigh frequencies by ,tlieflow quencies.

f .Another feature is the use of rec eivi g circuits for thearnplificatio nand rectification o'flthe variously modulated high;fretain automatic operations in the establishing of a connection may beinsured under the most adverse conditions encountered in the Ioperationof systems of this type.

Another feature resides in the provision of a circuit arrangementwhereby the talking conductors in the cord circuit are completed, eitherto the operators telephone set should the talking key be operated ortothe connection beyond, between the sending of sets of dialing impulsesso that both visual and audible supervisory signals may be received overthe toll line during the dialing period.

Anoth'erfeature resldes mthe provision of means in the cord circuit anddiahng cir- ,eeit equipment whereby visual supervisory signals. such asbusy indications may be received. during the dlaling period regardlessof whether or.not dialingimpulses are being sent out over the line atthe, moment.

I V The arrangement is such that the line conductors are maintainedlooped through a repeat ng coil to the dialing circuit durlng thetransmission of impulses "so that any ..incoming signal will not beinterfered with as might be the casewhere impulses are transmitted .bythe openin'g'and closing of the lineconductors.

The nature'of the invention will be more fully understood fromthefollowing de scription read in connection with the accompanyingdrawings, in .which Fi 1 shows diagrammatically a connection from asubscribers. line with a toll operators cord circuit and an associateddialing circuit arranged in accordance with this invention and locatedat one manual exchange.

a By meansofthis equipment, a toll operator 40 may extend connectionseither to another toll operator. located at another manual ex change'orto a subscriberreached throughan automatic or. machine switchingexchange. Fig-2 represents the outgoing end of. a special toll lineequipment arranged in accordance-with this'invention and located at theoriginating exchange and by-means of which voice frequency alternatmg'current signals may be transmitted to and received from thedistantexchange over any type of toll line associated therewith. Fig. 3represents the incoming end of a special toll line equipment arrangedinaccordance with this invention located at a distant exchange andportion of the equipment at this exchange andat an automatic exchange bymeans i by means of which voice frequency alternating current signals ofthe type employed in this system may be received from or trans-'llllttGCltO the originating exchange. Fig. 4

represents the local equipment at' this distant exchange by means ofwhich a manual connection may be extended from the incom ing toll lineequipment. Fig. 5 represents a which automatically called subscribersmay be reached from the above mentioned toll line equipment. Only asufiicient portion of V the automatic exchange has been shown to form abasis for a full explanation of the invention involved. 1

Referring 'now to the drawings, trafiic over the system as illustratedand arranged 111 accordance with this invention may be outlined'asfollows: If it is assumed that a subscrlber at has established aconnection as far as to the toll operators position 100 and the tolloperator has inserted the answering plug 12 of the cord circuit shown at100 into jack 11 and ascertained the number of the desired line, thetoll operator will then insert calling plug 15 of the cord circuit intojack 2100f the outgoing toll line equipment 200 which is associated witha toll line 220 leading to the incoming toll line equipment 800 at thedistant exchange. The toll operator at then proceeds in either one oftwo'manners to extend a connection.

If the wanted subscribers number can onlybe reached through the serviceof a toll 'operaton'such as the one at position 410 at the distantexchange, she proceeds to call this toll operator in the usual mannerwell known in the art except that alternating V currents withinthevoicerange offrquencies on which alternating currents of lowfrequencies are superimposed, are used for the necessary signalingindications. I That is, she causesinstrumentalities in the cord circuitand the outgoing toll line equipment 200 to be operated to transmitvoice fre quency alternating currents of, for example, 1000cyclesmodulated by analternatlng current of 135 cycles over the tollline 220 to the incoming toll line equipment 300 at the distantexchange. Such signals then condi tion the incoming tOll'llIlG equipment300' for a manual connection and are translated by the receiving circuitequipment 350 into nection, as well as when the connection isestablished. 7

Similar operations take place in the systern if the toll operator atposition llO' desires to call the toll operator at position 100 when,for example, the same type of signals hi are produced at the incomingtoll line equipment 300, transmitted over the toll line 220 andtranslated by the receiving circuit equipment 250 at the outgoing tollline equipment 200 into signaling indications for If the attention ofthe toll operator at position 100. r

On the other hand, if the'wanted subf s'cribers line may be reached froman automatic exchange, such as the one indicated m in Fig. 5, the tolloperator at POSltlOIlalQU proceeds by operating a dialing key to connectthe common dialing equipment 150 to the cord circuit and by means ofinstrumenrents of 1000 cycles modulated by various low frequencycurrents, to cause various supervisory signal indications 'to be givenduring establishment and disestablishment of the connection Thearrangements of the toll line equipments are such that various signalsfor the supervision of the automatic connection are transmitted back tothe operator at position 100 during the progress of the call as Well asin the breaking down of the connection. Such signals may consist of thefundamental alternating currents of 1000 cycles modulated by lowfrequency currents of 20 cycles or 135 cycles, or signal indicationsconsisting of the fundamental frequency modulated by low frequencycurrent of 20 cycles transmitted in the shape of impulses at 60 perminute, these latter impulsesbeing used when all of the toll linesarebusy; or signal indications consisting of the fundamental frequencymodulated by loW frequency of 20 cycles transmitted in the shape ofimpulses at 120, per minute, Which are used When the called'line isbusy. Such signals are all translated bythe receiving circuit equipment250 at the outgoing toll line equipment 200 into the proper supervisorysignal indications for the attention of the operator at position v100. i

It is to be understood that the various frequencies mentioned are simplyillustrative and that the invention is not limitedto the employment ofthese particular values but that any frequency Within the voice rangemay be used for the fundamental alternating current, and lOW frequencycurrents of other frequencies more suitable to particular cases in thepractice of the inven tion mayalso be selected.

It is believed that the arrangement shown will be more fully understoodfrom the following detailed description of a series of calls of thetypes that may be completed thereby. The first type of connecti'ons'tobe considered Will be calls extending on the so-called ring-down basis,that is, from a subscriber 10, through a toll operatorsposishown as theyform no part of this inventlonand as it 1s Well known and understood inthe art how manual connections are attended to by outgoing as Well asincoming toll operators,'no furtherexplanation ill be made in thisrespect. assuming then, that the operator at 100 as inserted plug 12into jack lllan'd has ascertained thenurir ber of the Wanted subscribersline by the connection of her telephone'set to the. cord circuit, andthe operation of listening key 82,'slie proceeds by inserting plug. 15into jack 210 after having performed the usual busy test. asa'result'o'f this action, relays 24, 23 and 201 are operated'asfollowszbattery, Winding of relay 245, Winding of relay 23, sleevecontactsofplug .15a1'id jack 210, Winding of relayi201to'ground'fTheop'eration of relays 24fand' 2 3 closes the following circuits: onefrom battery,,armature and front contact of relay 2fl, Winding'of relay26, armature-and back contact of relay to, ground, another from batteryat any 12 3 lamp 25,.armature and front contact-of relay 23, armatureand b ackconta ct ofrel ay 26 to ground at thenormal contactsvOflistening key 32 and another from battery re lay 2.4, Windingbf relay2'? to ground: listening key32, these latter tWo circuits are, however,prevented from lighting lamp 25 andoperating relay27 as relay 26operates ratherquickly. sothat these circuits are almost immediatelybroken, The operation of relay 201 closes anaenergizirig circuit forrelay 202 from battery, outer right hand armature and front contact ofrelay20l, Winding of relay 202 toground, Relay 202, when operating,closes a'circuit for busy signals 205 as followszbattery, right handarmature and front contact of relay 202, winding .of, signals 205 toground, operating these signalsto indicate toother toll operators thatthe toll .line 220' connected tvith this equipment is busy.

The operator now proceeds to ring the operator at the(llStQlllQQXGlltlllgQbY actuat 4 ing ringing key 34. This causes a 20cycle.

alternating current source to be connected to the ring lead and groundto the tip lead of the cord circuit and the outgoing tolllinc equipmentin Which abridged circuit con;

taining an alternating current responsive relay 208 is located. Belay208 responds to the 20 cycle current andcloses a circuit as follows:battery, armatureand front contact of relay 208, winding of relay 209loground. Relay 208 also, by operating this armature removes battery fromthe 20 cycle alternating current Iresponsive relay 204-111 the receivingcircuit 250 in order :that'thisl equipment may not be disturbed theringing current from the cord circuit; Relay 209 operates in the abovetraced circuit and closes a circuit for relay 213 as follows: battery,upper armature and front contact of relay 209, winding of relay 213 toground. Relay 213, in operating, disconnects the outgoing end of thetoll line from the tip and 'ringleads to the jack 210 and connects it tothe source of fundamental high frequency alternating current on which issuperimposed a low'frequency current of 135 cycles. The application ofthis signal to the outgoing line is accomplished as follows: It shouldbe noted that the fundamental alternating current source 211 of 1000cycles is connected to one winding of transformer 214 while a source oflowfrequency alternating current 212 of 135 cycles is connected throughthe lower armature and front contact of relay 209 to another winding oftransformer 214 whereas a third winding of this transformer isconnectedto the leads now connected tothe upper and inner lower armatureand front contacts of relay 213. The signal is, therefore, transmittedover the toll line 220 to the incoming equipment- 300 received at thereceiving circuit equipment 350 and 18 there transmitted through theinput transformer 326 to the input circuit of the vacuum K tube 327serving as an amplifier. The plate circuit of the tube 327 is connectedthrough to the grid or lnput clrcuitof vacuum tube 328, whichacts as arectifier, causing the relay316, whichin turn is connected through r thtransformer 329 in the output circuits of the tube to operate inresponse'to the 1000 cycle current modulated by the 135 cycle current.That is, relay 316 and the circuit therefor are tuned to respond to thistype of signals only in a manner well known in the art. As this relayattracts its armature an obvious circuit is closed for relay 217 whichin operating closes a circuit to ground for 0 lead 330 to cause theoperation of relay 401 as follows: battery, make-before-break contact ofrelay 408, left-hand winding of relay 401, lead 330, lower armature andback contact of relay 319, outer right hand armature and back contact ofrelay 307, lefthand ar- 2 mature and front contact of relay 317 toground. The operation of relay 401 closes a circuit for the busy signals426 at the jacks 425, 430 and 429 of the toll line as follows: battery,at relay 408, left hand ara mature and front contact of relay 401, busyright-hand armature and front contact of relay 401, left hand armatureand back contact of relay 404, right-hand armature and back contact ofrelay 411, lamp 427 to ground, causing this lamp to be lighted toindicate to the operator at 410 that her attention is desired on thisline.

In answer to this signal, the operator at 410 inserts her plug 428 intojack 425, causingrelay 402 to operate over the following circuit: batery, sleeve contacts of plug428 and jack 425, right hand winding ofrelay 402, lead 431, inner right hand armature and back contact of relay307 to ground. The operation of this relay opens the locking circuit forrelay 401 which is presently released on the subsequentoperation ofrelay 408 causmg the supervisory signal 427 to be extinguished. 'Thatis, relay 408 is operated by the closing of anobvious energizing circuitat the armature and front contact of relay 402.. The operation of thisrelay thus in addition to opening the original energizing circuit forrelay 401 also closes a circuit for maintaining the busy signals 426operated over the following circuit: battery, armature and front contactof relay 408, busy signals 426 to ground. The operation of relay 402also applies battery to the lead 432 which causes the operation of relay319 as follows: H

battery, armature and front contact of relay 402, lead 432, winding ofrelay 319 to ground. The operation of relay 319 closes the tip and ringleads of the toll line to the tip and ring of jack 425 at" its upperarmatures and front contacts and disconnects the tollline from the leadsto the automatic equipment at the back contacts of these armatur-es. The

operation of relay 319 also opens the cir-w cult for relay 401 which, ashereinb-efore listening key connecting her telephone set in the usualmanner to the cord circuit and receives the details of the call from theoperator at 100 who has also by this time actuated her listening key 32and connected her telephone set to her cord circuit. The operator at 410then proceeds to extend the connection to the wanted subscribers lineand call the subscriber and the connection with the calling subscriberis also attended by the operator at 100, in accordance with the wellestablished practice in the art of telephony.

Conversation between the subscriber at 10 and the called subscriber maythen take place. a i

In case the call extended to the operator at 410 is intended for asubscriber that may be reached through the assistance of an operator atanother distant exchange, that is, if the operator at 410 is merelyemployed as a connecting operator fora so-called through supervisorysignalsf-rointhe operatorat 100 r at the ori inatin exchan e-oyer thetoll line b D 2D 7 220 thro'ughthe incoming toll line e ui ment 300 tothe cord circuitof the operatorat-.410

and this may be done by the operation of the ringing key 34 wheneversuch super- Vis'ory slgnttllllgiS desired. 'The functionof the circuitin this instance is the same as that already described when thekeywasfirst operated, except that when relay'317 is now operated in responseto a signal, over the toll line220, of 1000 cycle alternating currentmodulated by a 135 cycle current,

the ground 'at the left 1 hand" armature and 1 front contact' of thisrelay operates relay 320 as follows: battery, winding of relay-320',lower armature and front'cont'act of relay 319,.0uter right: handarmature andback contact of relay 307, left hand armature and frontcontact of relay 317 to round';cau'sing the operation of relay 320; lhiscauses the disconnection of the tip and ringleads of the toll line 220and connects currentfrom the 20 cycle alternating current source 331"and ground to thetip and ring leads ofthe switchboard endof the incomingtoll line equipment through the ack 425 to the cord cir'cuit of theoperator'at' 410, causing supervisory signal indications to bedisplayedi n the cord circuit at 410 and theconnectionmaybe extendedfurther as is welll'znown-in the art. I

In case the incoming operator at 410 at the distant exchange decides toenten'dfa connection to a subscriber that may be attended to by theoperator at 100, i. e. a connection in the opposite direction'on thetoll line 220, a procedure similar to that described above is followed.Theope'rator at 410 afterinserting her plug 428, into jack 429causingo'perations totake placeresulting in the op} eration of relay319; a'ctuates her ringing key (not shown) in the same manner as theoperator at'100 operated her ringing key 34:. Twenty-cycle alternating,current and ground ,is thereby connected to the; tip and ring leads ofthe toll line equipment 300;

causing relay 332 bridged across the lineft-o operate. The operation ofthis relay closesa circuit for relay 310 as follows: battery, right handarmature and front contact of re lay 332, winding of relay 310' toground.

This relay after havin disconnected the u i 7 H s a ,i portions of thetip and ring leads connected to jack 4-28, connects at its upper andinner lower armatures and front contacts, leads connected through oneWinding of a re eae ing coil 336, another winding of thisco'ili'sconnected to analternatin'g current source 33athaying afrequency-of 1000-cycles, while a third winding 1s connectedto analternat ing current source 335 having a frequency of 135cyclesandthatis nowconnected through he inner left hand a rest-lire and'f i ont con-'- mer er-aw 332. Thus, anLimpulseifrom the --1000"cyclesource 1 modulated bycurrent from the 135-cycle source'iseffectivethrough the-tip: and 'rin'g leads ofutolliline 220', and;

transmitted at the outgoingtollline equip- 1nent=20'0; through the upperand inner lower a-ri'natures and backcontacts of relay 213 and v atthe-receiving circuit250 through the in.-

put transformer 230 to the. input circuit of the v'aeu'uinl-tube 231.:Thisireceiving cir-.

cui'tis similar to the receiving circuit 350, that is, the plate circuitof; the amplifier tube 231'is connected to the grid or lIlPUbClIClllt ofa secon'd tube 232, which acts as a rectifier cau's1ngre1ay221 which isl'nturn connected through the transformer 235 in the output circuit ofthetube, to operatein response to the 1000 cycle current modulated bythe 135 cycle current: The operation of-r el'ay 221 closes. a circuitfor. relay 222 .as follows: battery, left hand winding ofI-relay222,inner right-handiarmature and back contactfof relay 201,:ar1nature andcontact of relay 221 to ground. Relay 222, in operating, closes, atit'sleft-hand armature. and' front contact,-

ture and back contact of relay- 227, lamp 226;

to-ground, causing the illumination of this lampa's an indication totheoperator at 100 that the connectionis desired on this line.

In an'sweringothis signal, the operator at 100 inserts-plug. 15'intojack 228 and relays 24, 23 an'd 201 are operated 1n a circuit ashereinbefore traced; the operation of relays 24 and 23in the cordcircuit have also the same effect as hereinbefore descrlbed, i. e.,tl1at-la1np'25 isnot illuininatedbut the operation of relay 201 byopening 1ts make before-break contacts to battery, causes thesignalf226to=be extinguished. The operation of relay 201 also causes therelease of relay 222 and the operation of relay 202 which thus maintainsbusy signals 205 oper ated over anobvious circuit. The operator at 100now'actuates her listening'key 32, connecting her telephone setto thecord circuit and r'ec'eives the details of the-callfrom the operator at410 who has already by this time actuated her listening key:correspond-vingto 32 and connectedzher telephone set 39 '90 acircuit-for'the busysignals 205 as follows:

subscriber in accordance with the well estab lished practice in the art,of telephony whereupon conversation between the sub- 'scriber at thedistant exchange and the subscriber at 10 may take place.

In case the call extended to the operator at100 is intended for asubscriber that may be reached through another exchange in thisdirection, i. e., if theoperator at 100 is merely employed as aconnecting operator for a through connection, it maybe necessary to sendsupervisory signals from the operator at 410 at the distant exchangeover the toll line 220 through the outgoing toll line equipment 200 tothe cordcircuit of the operator at 100. This may be done by the operatorat 410'actuating her listening key whenever such supervisorysignaling-isdesired. The function of the circuits in this instance isthe same asthat already described when the ringing key was first operated exceptthat when relay 221 was operated, instead of operating relay 222, acircuit is completed for relay 223 as relay201 is now operated. Thiscircuit may be traced as follows: battery, winding of relay 223,

' inner right-hand armature and front contact ofrelay 201, armature andcontact of relay 221 to'ground. The operation of relay 223 connectscurrent from a cycle alternating current source 224 and ground at itsarmatures and front contacts to the tip and ring leads and contactsofthe'jack 210 and plug 15 to cause the operation of relay in the cordcircuit at 100. The operation of relay known in the manual telephoneart.

The second type of connections to be considered are calls extended onthe so-called automatic basis, i.'e., from the subscriber at 10 throughthe toll operators position at 100 at the originating exchange, over thesame toll line 220 to the incoming toll line v equipment 300 which will,in this instance,

be prepared to extend the call through an automatic equipment such as isshownin Fig. 5 and through the associated switches to a subscriber suchas 510. Asthe automatic exchange equipment does not form any part, ofthis'invention, only a smallportion has been shown suflicient toillustrate .how it is effected by and how it reacts upon the toll lineequipment in accordance with this invention. In fact, any well knowntype pf automatic equipment may be used as long as the proper signalindications may be sent. or received to perform the proper functlonswlth respect to dialing and signaling super a visory' indicationsthrough the toll line equipment.

Assuming then, as hereinbefore, in connection with calls extended on thering-down basis that the toll operator at 100 has inserted the plug 15into jack 210 and relays 201 and 202, signals 205', relays 23, 24 and.726 have all been operated and that the,

contacts, of relay 38. Relay 37 in operating disconnects the tip andring leads'of the cord circuit from the plug 15 and connects theretoleads 40 and 41, the other ends of which are connected throughright-hand windings of transformer 42. Another circuit is completed forthe operation of relay 43 as follows: battery, winding of relay 43,inner left-hand contact of relay 38, upper contacts of dialing key 35 toground. Relay 43, inoperating, closes a circuit for relay 38 as follows:battery, winding of relay '38, right-hand armature and front contact ofrelay 43 to ground at the upper contacts of dialing key 35, causing thisrelay to operate. It should be noted that when the dialing key wasoperated, a circuit for the upper lefthand winding of transformer 42 wasclosed as follows: from battery at the alternating current source 44,upper. left-hand winding of transformer 42, contacts 48 of dial 46,upper contacts of dialing key 35 to ground. As this source 44 includes avibrator operating at, for example, 1000 interruptions per second, a1000 cycle alternating current is inducedin the upper left-hand windingof transformer 42 and transmitted to the tip and ring contacts of plug15 to the toll line 220. This impulse of high frequency alternatingcurrent is, however, discontinued the moment relay 43 is released whichtakes place as soon as relay 38 is operated. Relay 43 is released by theopening of the inner left-hand make-before-break contactsof relay 38,whereas relay 38, in operating, pro- Vides a locking circuit for itselfthrough its inner left-hand armature and front contact to the ground atthe upper contacts of dialing key 35. On the operation therefore, ofrelay 38 and release of relay 43 a circuit is completed from thealternating current source 44, through the lower left hand windg oftransfo r the r ght armatur l er-7541 4.

passing through the two left-hand windings of the'tra-nsformer 4:2 inopposite direction and consequently no inducedcurrent is effectivethrough the secondary windings of the transformer under this condition.The

cycle'of operation of these relays therefore providesthat theimp'ulseproduced in this manner is of a sufiicient duration to'insurcthat the required operations willtaken place under all circumstanceseven though the functioning of the individual devices and circuits maynot be entirely up to the standard, that is, the operation hereinafterdescribed will have suficient tirne to'be performed. It should bepointed out that the length of this impulse is always the same andisproduced by this simple cycle of operations of the above mentioned tworelays a3 and 38 only without the use of any involved ti'rning' relaycombinations. This high frequency alternating current impulse at afrequency of l000cycles is'now received at" the incoming toll lineequipment 300 through transformer 3 26 bridged across the tip and ringleads. After having been transmitted through the amplifying tube 327 andrectifying tube 328, thisiinpulse causes the operation of relay 301,which responds to a rectified current "from an alternating current atthis frequency only.

The operation of relay 301 closes a circuit for relay 302' as follows:battery, right hand armature and back contact of relay 317, winding-ofrelay 302, oute'r'left' hand armature and back contact of relay 306,annature', front contact of relay 301 to ground at outer left handarmature and backv contact of relay 332, causing'the operation of thisrelay. Relay 302 in turn closes a circuit for busy signals 426, frombattery righth'a'ntl armature and front contact of relay 302, lead436,signals 426 t'o' ground, making the manual end of this trunk circuitbusy. The operation of relay 302'also opens a circuit normally extendingthrough the right hand winding of polarized relay eoawhieh niay betraced as follows: battery, left hand armature and back contact of relay302, arn'iature and back contact of polarized relay 303,v right handWinding of relay 303 to ground. This circuit iiorinally holds relay 303in'the non-operated position shown, asthe current through a circuitclosed for the left hand winding of relay 303 from battery, armature andback contact of relay 305, Wind ingot relay 304:, left hand winding ofrelay 303 to'ground'normally opposes this current through the right handwinding of this relay and relay 303 is therefore now per mitted tooperate. The operation of relay 303 applies, atits armature and frontcontabt as Soon as-the inipu1se fronr the" di'aliii g circuit' ceasesand relays 301 and 3021bleasefa short circuit forrelay' 304 which-, itshould be noted, isnerman'y operated, i. e.- the current from the lefthand amimtare amr back Contact of relay 302 now passes tlireuglr thearmature and "front Contact of relay" 303 to the left hand 'winding ofrelay 303 to ground.- Relay 304, the'refore, in I releasing, follows:battery, 'lnake before-brealr contacts of relay 108,-le'ft hand armatureand 'back' closes-a circuit for relay 305,-" as' contactof relay 401,'le'ad '4aaae'maaae and back contact of relay 304, winding of relay 305;left hand winding of relay 3 03- to ground. The operation" of relay 305closes ac'ir'cuit for relays 306' and 307-as follows: battery, arniatureand front contact of relay 305, windings of relays 306 and 307 in seriesto groundi The operation of relay 307 by closing its'left hand armatureto the corresponding front contact, retains the busy signal 426 operatedafter-relay 302is released through a circuit as follows z'battery, lefthand ari'na'ture and front contact ofrela'y307, lead eeemgroma atthebusy signal 426. The operation of relay 307 also includes aresistance to bat tery in the lead 431by removing the ground 7 at itsinner right hand armature and" back contact as"follows: battery,armature and front contact of relay 305, resistance335 and lead 4531, tomake the sleeve" leads of jacl'rs' 4'25 and 429 busy. The ground atthe'innerright hand arina'ture of relay 307 is now applied at the frontcontact therefor'to a conductor 550 leading to the autninaticequipine'nt shown-'injFigJ 5. The result of thhigh frequencyalternating? current iinpulse sent fron'i dialing" equipment 150* istherefore that a ground is" applied on lead 550 to prepare the automaticequipmhtforthe reception of directive and supervisory impulses and whenthis equipment is se'i'z'ed as hereinafter described a signal isreturned therefrom and the'dialiiig inayba gin. 1 The effect of thisground on lead 5f'50is as follows: Relay 511 is' operated over thefollowing circuit: battery, winding of relay 511 to ground at lead 550.The operation ofrelay 511 closes a circuit as follows: battery, relay512; inner right hand arii'iature; and contact of relay 514, armatureandback contact of relay 522', left hand armature and" front contact ofrelay 511 to ground. This causes the operation of relay 512 which inturn closes an obvious circuit for rotary magnet 518 of the finderswitch F. The rotary magnet 518' in operating, c'au'ses'the lineswitchFtostar-t hunting for an'idle district switch in a manner Wellknown in the art.

Nith an idle district switch, such as is diagrammaticall illustrated atG and the idle condition which is designated by the presence of batteryon the test terminal 520, relay 522 is operated in a circuit extendingfrom battery, sequence switch contact 540, armature and back contact ofrelay 525,

terminal 520 and wiper 521, right hand arcuit for relay 514 as follows:battery, wind ing of relay 514, armature and innerfront' contact ofrelay 522 to ground at the left hand armature and front contact of relay511. Relay 514, in operating, closes a locking circuit for itselfthrough its inner left hand,

armature and inner front contact to the ground on lead 550. Relay 514,at its two outer left hand armatures and front contacts closes the tipand ring leads from the brushes 598 and 545 of the switch F to relay 527and lead 552 for purposes hereinafter to be set forth. Relay 514 at itsleft hand inner armature and one front contact closes a circuit forrelay 525 as follows: battery,

winding of relay 525, brush 541 of switch F, left hand inner armatureand said front contact of relay 514 to ground on lead 550, causing theoperation of relay 525. Relay 525, in attracting its armature,removesbattery from the test terminal 520 of switch 1 whereupon relay522 releases, and as relay 514 is held operated, the ground from theleft hand armature and front contact of relay 511' through the armatureand back contact of relay 522ihas no effect on relay 512 .or magnet 518.

The operation of relay 525 of the selected 7 district switch causes anidle sender to be selected in a well known manner, and when relay 500operates from the ground at relay 332 over lead 552, relay 501 is alsooperated through int ermediate'relays (not shown) to cause a dialingsignal to be given to theop- .erator at 100 in the following manner.Relay 501, in operating, places a ground on the tip conductor of theswitch Th s ground causes relay 527 to operate in a c1rcu1t extendingfrombattery, outer right hand an mature and back contact of relay528,winding of relay 527, left hand outer armature and front contact'ofrelay 514,, brush 598, sequence switch spring 580 to ground at thearmature and front contact of relay 501. Relay 527, in operating, causesthe ground on l ad 55!) t9 be c nne ted t9 con uct r 55? 310, inoperating, closes a circuit through its upper and inner lower armaturesand front contacts from the left hand winding of transformer 313 to theincoming tip and ring leads of toll line 220, thus transmitting animpulse from the 1000 cycle alternating current source 334 modulated bycurrent from the cycle source 331 by means'of the upper right handwinding of trans former 336. -This impulse, however, is of shortduration as the operation of relay 310 closes at its outer lowerarmature and front contact a circuit to ground at right hand armatureand back contact of relay 404 for the left hand coil of relay 311 frombattery at the right hand armature and front contact of relay 309,causing relay 311 to operate its armature in the opposite direction andthus opening the energizing circuit for relay 310 which is therebyreleased and causes.

the impulse to cease. This modulated signal causes the lamp to becomeilluminated to indicate to the operator at that dialing may, begin. Theimpulse is received at the receiving circuit equipment 250 over thefollowing circuit: from the left hand winding of transformer 313 throughthe tip and ring conductors of the toll line 220 to the incoming windingof transformer 203 andis effective through the receiving equipment 250in the manner hereinbefore described for other signals to cause theoperation of relay 204. The operation of relay 204 opens the closedcircuit from battery at the left hand armature and front contact ofrelay 7 201 through the left hand winding of polarized relay 203 toground, causing this relay to operate as the current through the closedcire cuit through the right hand winding of relay 205 normally opposesthe current in the left hand winding. This latter circuit may be tracedas follows: from battery, left hand armature and front contact of relay201, left hand armature and back Contact of relay 207, winding of relay200, right hand wind in of relav 203 to round. In oan/rating this relayprovides a locking circuit for itself through its right hand winding,armature and front contact to battery at the left hand armature andfront contact of relay 201 as soon as relay 204 is released when theimpulse from the incoming toll line equipment 300 cea e Thelastmentionedv cir it flows short circuits relay 1206 which istherehydcenergized. AlCltGLllt is now closed forrelay 207 follows: battery atrelay 201, arrnat11I'-8:3,'I1 Cl back contact of relay 206, inding of;relayi207, leftzhand inding of relay 203 to ground. opens ia shunt.circuit through its right-hand The operation of relay 207 armature andbaclrcontact, {or the left hand high resistance winding of-grelay 2.0-11thusincreasing the resistance for thesl-eeVe-Acircuit sufiic ently tocause relay 23 to release and close .a circuit for lamp at itsarina-ture and hack contact [to ground from battery ,at relay 24. I hiss gnal, tnow indicates to the operator :that diahng operations nlay begn.

Current from the 1000 cycle source 44 at the dialing circuit l50is nowinposition to he connected-to the receiving-circuit 3.50as a pulsingcurrent. When,-therefore,the operator at 100 operatesthe dial 46inaccordance Withthe number of the desirevd line, ground is connected-tothe Winding of relay 37 fro m the off-normalcontacts 47 of'the dial,caus-' ing relay '87 to operate-over obvious cir- 1 suit. The operationof this relay closesa circuit from the leads 40 and {ll of the tollline/i22 t th upp end-lo e igh ihand' windings of transformer 42' theleft hand windings of which are closed from the source 44 to thesgroundaat the upper contacts of di ling ikey i3 2, e l r winding th ug the.right;ha11d armature and front contact of relay38, which .is operatedat this tirne,

and thenthrough the right hand armature and hack montaot of .relay' Q3and 1 the upper wvinding throughthe pulsingmontacts 48 of dial 46.lrnpulses of lOOOcyclecurrent from this source are therefore now readyto be transmitted to the receiving equipment :350

at 300. The pulsing contacts 48 of=the dial are opei atedduring thereturn of therclial to normal in accordance with the desired numherandtherehy cause an interruption of the circuit through the upper left handWinding .ogftranstormerlQ-to the; source 4& and in this manner pulses oflOOOcycle current :are transmitteditogthe distant end each pulsebeingjeq-ual intin e to theopen periodof the pulsing contacts 48 of-thedial. SVhem-therefore, the 100.0 cycle pulsesare received over the lineafromthe outgoing end, they are transmitted through the receivingequipment 350 v, as hereinheforedescribed ttO cause relay 30l1t0operateand release ata ,ratecorresponding .to the rate of interruptionsof the pulsing contacts 48. Relayv301 thusdi-sconnects at its armatureand back-contact the ground at .relay 332 from lead 552-to causeselecting operations v to he performed by the automatic exchange.equipment shown in Fig.

5. That is, arelayi50O is caused :to respond to filfielllllllllSGS overa circuit as follows:

attery, nd n of ra sins ay equence switch 58y1,-=Wiper 545, of switch:F, middle upper. armature and ifront contact: or

1th? c r u o re-l y 5 4c, inn-er sinne ar atur 59n bask ont c z re ay 2.28,, lsefl1 52 a mament back cont c 'd-rel y tats-re ed a th ne I uppea m u and ack n ni -firs .e rel y 2- inatic equipment when t-l1B pUle5-Lr6 registered in the sender ground is removed from th ip lea-d lay: 01,Eth hy a ing ir ey .2 to re a wh ch i tern 91 1 1 1 9 circuit to groundover :lead for -.relay 399- ;R lay 5 09, n re eas n sqlo e a' r ui Toturn now to the operationrof tlie autof r re ay 101 fqllowsat er y, fight iha t ar u Eaid ba k $01 M 6 Err et 3 9 been registered on thesender f It isjhou ldibe stead that in this ase on, th Operat i ay 2 cml th wirin eau pm n vzfim r ilay 205 :is;pern 1 itted to: release. Eh entliis mp lse cea es and r ay 2 1 315 'QSi l n rmal, a shun ieu sestablishe 2 i armatu an aback c tes -1f0 r lay 2 aus ng th re ay torele se, her by e ta lishingqthe unt ir ui or it ilet han winding o t -rlay 2 r a t agai we th margina relay 2 t iepe at d ope iba-ek contact. ry

QWhen the wanted subscribers line a tL5,10

is reach-ed, ground;isconnecteil atijtlhe contact 52 .tB- m Seq enc wich on c towiper 538 genie switch E; whereupon ,relay 528 isoperated in acircuit Wl11f l1111ay;b

7 signa a its a ma u and I traced from hattery, Winding of relay 528,

nialreebeforeehreak colltactsfloif relay 528, Outer right hand armatureand 'ba'ck con gtactpf relay 515i, brush538 =.to thegground' at contacts.582. {At-itsinner rightlhandarniaim an i n te act, r ay 28 stablish..;a locking circuit iorlitself to the groun d ,on

.iconductor ,550. ,At ,its outer iright hand armature .anchback contactthisitelay opens the energizing circuit "for .r lay 2 and a it innerleft hand armature :Iand'back contact, rela-y,528 opens the daling:concluctor'552 ior ,pulsingxrelay' 500.7 :At ,its outer leftjhantlarmature and front contact, relay 528 establishes a circuititromgroundat conductori'fioll to the ,con'ductor 553, thus closing cuit;forrelay 318 ,as ''follo s hatter-y, nd-

"ingnof relay 318, makeThefore hIfeak contacts I of relay 31S, conductor.outer left hand ,arniatnre :and' front contact of relay 528, toground-ion conductor 550. Belay 318, an

operating, closes at locking circuit for itself ,throughiits Qleft-handflarnjia'ture and front a contact directly to ground at conductor550 and'at its right hand armatures and front contacts extends the tipand ring leads from the toll line equipment 300 to the tip and ringleads connected at brushes 598 and 545 of the switch F.

If the wanted subscribers line is idle, the

ground connected at contact 529 is now completed at the middle upperarmature and front contact of relay 528 to conductor 551 causing theoperation of relay 309 which through operations as hereinbeforedescribed causes an impulse from the 1000 cycle source modulated bycycle current to be transmitted to the toll line 220 through thereceiving equipment 250 and causes the sequenceof operations of relays204, 203, 206

and 207 as hereinbefore described to light the lamp to indicate to theoperator'at 100 that the called subscriber is idle and that ringingoperations may begin. 1

When, therefore, all the digits corresponding to the'number of thedesired-line have been dialed, the operator at-100 may a restore thedialing key and ther b lease relay 39 and disconnect the dialing circuit150 from the operators cord circuit.

As the operator at 100 is now connected to the wanted subscribers lineshe may sig nal the subscriber by theoperation of key 34 and circuitsare established in the same manner as described with callsestablished'on a ring-down basis, i. e., an impulse from the i 1000cycle source 211 modulated by current from the 135'cycle source 214 istransmitted from' the outgoing toll line equipment 200 over the tollline 220 to the receiving equipment 350, causing the operation of relay316 and through the contacts and armature of this relay, relay 317 isoperated over the following circuit: battery, winding of relay 317,contact and armature of relay 316, armature and back contact of relay315, outer left hand armature and back contactiof relay 332 to ground.The operation of relay 317 closes .a circuit to ground for conductor 554causing the operation of relay 599 over the following circuitzbattery,winding of relay 599, sequence switch 594,brush 597 of switch F overlead 554, outer right hand armature and front contact of relay 307, tothe ground at the left hand armature and front contact of relay 317. Theoperation of relay 599 1000 cycle source 334, modulated by current fromthe 20 cycle source-331, to be, transmitted to the cord circuit at tocause lamp ground.

25 to be extinguished by a series of operations as hereinbeforedescribed, to indicate to the operator that the subscriber has answered.Conversation may now begin between the subscriber at 10 and thesubscriber at 510 as the operator at 100 will,as is well known in theart, establish a connection through plug 12 and jack 11.

At the termination of the conversation, the subscriber at 510 uponreplacing the receiver on the switchhook again causes ground to-beplaced at contact 529 of switch F from contact 582 thereby operatingrelay 309 and an impulse of 1000 cycle current modulated by current fromthe 20 cycle source to be therei by transmitted as hereinbeforedescribed to light lamp 25 as a disconnect signal. The operator at 100now proceeds to take down the connection by withdrawing plug 15 fromjack 210. As a result-of this action, l relays 24, 23 and 201" areimmediately released; -The release of relay 24 causes the release ofrelay 26 and the extinguishing of lamp 25. 'The' release of relay 201causes a signal from the 1000 cycle source modulated V by current from a20 cycle source to be transmitted'to the incoming toll line equipment300 as follows: When relay 201 releases, and before relay 202 has timeto release, a circuit is closed from battery atthe make-before-breakcontacts of'relay 201 through the left hand armature and front contactof relay 202 through the winding of relay 213 The operation of relay213,

to ground. which is slow to release, closes the toll line 220 to theupper winding of transformer 214 and an impulse from the 1000 cyclesource at 211 modulated by current from the 20 cycle source224 istransmitted to the receiving equipment 350. This causes-the operation inthis equipment ofrelay 301, in the manner as 'hereinbefore described bythe 1000 cycle current and the operation of relay 322 throughtransformer 311 and these relays in operat ing close a circuit for relay302 as follows: battery, right hand armature and back contact of relay317, winding of relay 302, armature and front contact of relay 315,outer left hand armature and front contact of relay 306, armature andfront contact of relay 301 to ground at the outer left hand arma tureand back contact of relay 332. The operation of relay 302 removesbattery from the left hand winding of relay 303, permitting this relayto release and cause the op eration of relay 304 and consequently therelease of relay 305 which breaks the energizing circuit for relays 306and 307. Relay 307 in releasing disconnects ground from lead 550 whichthereby effects the release of relay 31.8 and the'automaticswitchingequipment as it will benoted that relays 511, 514

and 528 are respectively locked from this The release of relay 307 alsoreleases the busy-signals 426 at the manual end of the toll line at thisexchange and removes in conjunction with relay 305 the busy potential onthe sleeves of jacks 425 and 429.

if, in the course of completion of the connection by the automaticexchange equipment the trunks through the switches 508,

509 and 511 for extending the connection are found busy,intermittentground is'connected to the terminal 529'from an interrupter,such as 583, or any other suitable means at a certain rate, for example,60 interruptions per minute. The first impulse to ground will operaterelay 528 and the following interruptions will release and operaterelay, 309,

at a corresponding rate to alternately close and open the circuit forrelay 310 through the operations of relay 311 as hereinbefore described.This causes impulses from the 1000 cycle source modulated hycurrent fromthe cycle source to be sent at the rate of per second. These impulseswill'ther fore intermittently light lamp 25 at. this rate in a mannerwhich is nowbelieved to be obvious. Thefiashing of lamp 25 indicates tothe operator that all trunks are busy.

In the same manner, if the called sub,- scriber is found busy, groundwill be con nected to terminal 529 at a different rate,

such as will produceim example impulses per minute from an interruptersuch as 584 and the flashing of thelamp 25 at this rate will indicate tothe operator that the wanted subscribers line is busy. As is well knownin the art,-both trunk "busy and subscribers line busy signals mayarrive'over the linewhile the-dialingis taking place. In accordance withthis inventio-nsuch busy signals may be effective in theqcord circuitduring dialing; that is, for example, incase abusy signal shouldarrive-at the cord circuit while the talkingkey is operated not onlywill the lamp 25 indicate this condition but also as soon as relay 3'?is released after a set of impulses representing'one digit is completedand the "talking conductors extended to the subscribers telephonecircuit, this busy condition will be aud'ibly indicated at the operatorsreceiver. The different typesof busy signals will, of course, in thiscase be identified by the operator by the rate at which the signals areinterrupted. On the other hand, in case a set of impulses rep--resenting asingle digit are in process of being transmitted the factthat thetal'king conductors are not interrupted but maintained asaclosed loop through repeating coil, thebusy signals will'bereceivedwithout interference through the receiving circuit 250 andoperate the lamp 25 accordingly. Therefore, regardless of whether or notdialing is taking place, a busy signal will be indicated at theoperators cord circuitin one form or another or both visually andaudibly. This may be of particular importance when numbers containing alarge num her-.oikligits are in process of being transmitted as in suchcases the operators time will be saved and a call abandoned at'the firstindicationof a busy. condition of the path selected.

lit should also-be noted -that lamp- 25 may be flashe'd by the calledsubscriber at the rate at which the switchhook is moved up and down.Relay 309- will then be operated-when the switchhoo-k is down andrelease when the switchhook is up. L

[If the operator at 100 desired to rering the called subscriber after he'hasreplacedhis receiver on the switchhoolr, she operates the ringingkey '34 and-the circuitsi'itunction in exactly the same :manner as whenthe wanted subscr'ibemwasfirst called, i. e., impulses from the 1000cycle source modulated by current {from the cycle sou-roe causingtheoperation ,of relay "31 7 which in turn causes the operation of relay599 which applies ringing current from source 3 592 through the establshed con-nectionto rering the wanted subscriber;

It now only-re1nai11s-to consider one more type of-connections that maybe extended by the use of this-tol llineequipment, namely,

a call intended iorWhat is commonly-known as the out delayed or repeatei"" operator, i. e. an operator-haying equipment arranged similarlyto the 1operator at/410 only that this op'e-rator is reached'bv havingthe operator at "100 dial a certain toll or special code number. In thiscase,*the operator-at 1'00 proceedsin the same manner as whendialingfior an automatic subscriber such the oiie located at 51 O.'0n lyinstead-of-reaching this subscribers line terminals she will beconnectedto terminals such as 010 connected directly to groundandbattery. This battery and lground are t1*ans1nitted*b ackover the lineand will causethe operation of relay 516. Relay 516, in operating,causes ground to be connected mead 55Tresulti-ng in the-operationofrelays and 401. "The operation of "these relays ca-uses the j lightingof signal lamp 405 as well as-the operation of thebusy signals 426.Relays 404 and 409 in operating provide locking circuits for themselvesto the battery at-relay 402 and the operation of relay 404 provides acircuit from this battery for signal 405, which in lighting calls theout-delayed operator's attention'to this trunk line, Relay401 closes acircuit for the busy signal 426 as shown.

The operation of relay 404 also removes the ground from the conductor489 and applies this ground on conductor 434-while the operation ofrelay 40-1 intermpts the battery; normally connected to -lead 433 toeffect-the release of the automatic equipment; that the removal ofbattery 1" :0111 lead 433 causes relays 305,, 30,6 and 807 toreleasea-nd the ground for lead 550,-to be removed, Whereas theapplication of ground atlead-4'84 operates the relays 309 and 310 tosend a signal as hereinbefore described and light lamp at the operatorsposition at 100 to indicate that the lamp405- at the out-delayedoperators position has been lighted. The

V removal of ground from the lead 439 serves the purpose of preventingrelay 331 from operating and releaserelay 310 until this out-delayedoperator answers the call as will hereinafter be described.

In answering this call the plug of this op- .erato rs cord circuit (notshown) will be inserted in the jack 430. Relays 407 and 402 will now beoperated over an obvious circu'it through the sleeve contacts of theoutback contact locking'circuits for relays 401 and 404 and closes atthis armature and front contact obvious energizing circuits for relays408 and 319. The operation, of relay 319 connects the toll lineconductors to the jack 430 While relay408, by operating its armature,prevents battery from being connected to the lead 433 andconnects thisbattery to the circuit for signals 426 to maintain these signalsoperated after relay 401 is released. Relay 404 in releasing opens theground connection for relay 409 and reestablishes the ground for relay311 which will now operate as it will be remembered that relay 309 ismaintained energized by groundvat relay 407 and relay'310 will thereforerelease upon the operation of relay 311 and cause the signal lamp 25 atthe operators position at 100 to be extinguished to indicate that theout-delayed operator is ready to communicate with this operator.

When the out-delayed operator disconnects by removing her plug fromjaclc430,

relays 407, 402 and 408 are released and all circuits arerestored tonormal condition, relay 30 9 naturally being also released causes thesignals to be transmitted as hereinbefore described to light lamp 25 asdisconnect sig nal for the operatorat 100.

It should be noted that in the event of the out-delayed operator is usedin a through connection, the operator at 100 may send supervisorysignals to this operators cord circuit by virtue of the operation ofrelay 317 and in case the out-delayed operator desires to call theoperator at 100 she may do so by moving the plug in and out of jack 430.

'There is another phase of this invention, namely a service observingcircuit arrangement the principal parts of which are shown at 380 andthe operation of which will now be described; It should be noted that inthe case of a ring-clown connection when relay 401 operates to lightsignal 427, the service observing signal 321 is also lighted over acircult as follows: battery, relay 402, right hand armature and frontcontact of relay 401, conductor 438, inner left hand armature and jack324 totoll line 220 through thecontacts and iii-matures of relay 323.When lelay 401 is released at the time the call is answered by the tolloperator at 410, the service observing lamp 321 is extinguished whilethe busy signal 322 is maintainedoperated with busy signals 426 throughthe operation of relays 402 and 403 until the connection is released.These operations in the service observing equipment 380 thereforeindicate the progress of a call on the ringdown. basis. i I r I On theotherhand, in case a connection is extended on the automatic basis, theservice observing equipment .380 operates in a different manner toindicate the progress of an automatic call. It should be noted that whenrelays 302 and 306 and other relays associated therewith. operate when apreliminary impulse of alternating current of 1000 cycles is sent outfrom the dialing equipment 150 to prepare the automatic equipment forthe reception of directive impulses, these relays close a circuit forthe service observing signal 322 as follows: battery, right handarmature and front contact of relay 302, busy signal 322 to ground andanother circuit for signal'321 as follows: battery, right hand windingof transformer 340, left hand armature and back conlill tact of relay309, inner left hand armature and front contact of relay 306, lamp 321to ground. It should be noted that the left hand winding of transformer340 is connected to the 20 cycle source 331 and consequently the circuitfor signal 321 is effected by an induced current from the transformer insuch a manner that a corresponding so-called quiver effect will beperceptible in the illumination of the lamp.

. This distinctive effect is taken by the service observing operator asan indication that a connection over the toll line 220 is to be extendedon the automatic basis while the busy signal 322 indicates that thelineis engaged. The service observing operator may now connect her set tothe toll line but as soon as the dialing begins, relay 323 is operatedto disconnect the operators set in order to insureagainst interferenceon the line during the dialingperiodo Signa1 321'- is lighted at thistinie u ith? a: steady illumination to -'-in'-' chcate the dialingperiod. It should bere-' membered that at this" time ground fromconductor 550" is connected to c'onductor 551" through the'operation ofrelay 527 and that relay "309 is'operated'inthis circuit. Circuits forsignal 321 and relay 32'3are,therefore,

closed as follows: battery,-right hand 'arma VVhe'n I the dialing iscompleted, relay. 527 1s released and ground on' conductor 551 is"removed so that relay 309 is'rele'ased" at this t me. vThe circuit forrelay 323 is; there fore, broken and the'c'irouit for signal 321*ist-ransfer'rd 'tothe right hand Winding of transformer 340; This stageinttlieprogress Y Qfi pa 'll'is, therefore, indicated y-" quiverindlcationof signal 321;

In case the trunk lines leading to the" wanted subscribers line arebusy-or the- Wanted subscribers' line itself-is busy; signal" 321 willalternately be'flashed from uiver to steady, respectively atth'erateof6001 120interrupt1ons per minute; due to the cor respondingoperations'of relay 309i on the other hand, when w theWanted--subscribers line has been reached, the"illuminationpf 1; signal321 will be' steady and when the celled subscriber hasanswered the-callsig= nal 321'Will quiver. At this" time, the" service observingoperators telephone 'setis" connected'to the toll line. In'case thecalled subs'crib'er operates" his switchhook to recall the subscriber at10st the operator at 100, the signal 321 alternately quivers or is madesteady inplia'se with the release and" operati'o'n of relay 3091 1 Whenthe disconnection tallies place tl'; tl1e called subscribers station,"signal 321 will ifuiver and the service observingoperators" telephoneset is disconnected to insure against interference Withthe disconnectsig n'al, Thus, it willibe seen that a convenient and simple method ofindicating and following the progress of an extension of either type ofcalls over the toll line available in this service observingequipment;-

hat is claimedis:

1. In a telephone system,"tliecombination of subs'oribers stations'witha 011 line ter-' initiating in means for extending the-line both'manua'lly and automatically to a; sub scribers station, a i serviceobserving system comprisingmeans responsive "during th op-' eration" ofthe said manual extensiom'means toindicate the progi'essof the manualcon ne'ction over saidlinei an'd means responsive to the operation ofthesaid autornatic eX tension means for indicating in a different mannerthe progressof'tlie automatic eXten sionover said line: I 1 y 2; In ateleph'one' system;- meansi for es-' tablishingi connections on a"manual basis, and means for employing alternating cur rents inestablishing"connections ona'an automatic ba'sis, serViceobserving-equipment in eluding: signaling means to indicate Whether aconneoti'on is being established on a manual-or on an automatic basisandalso the progressof" a connection being; established onthe automaticbasis: an; atelephone exchange system, a'line' circuit" opaque to lowfrequency currents,

means for establishing a connection either onamahualoran automatic basisover said line, apliirality of low frequency current sources, receiving?equipments responsive re spectively' to"cdrrents"frorn said sources, a;carrier frequency current for rendering said loW frequency currenteffective over; said line to control said rec'eiving equipments inautomatically establishingaconnection;

45;111". a telephone exchange} system, line circuits opaq'ne to currentsof lowfrequency, aplurality of low frequency current sources, a" sourceof" carrier frequency current and Ineans'for reiidering said currentseffective, v

toestablish' a connection either ona manual an automatic basis'oyersai-d line; circuits. 5:11; atelephone system, line circuits,opaque"tocurrentsof'low frequency, equip-Y. Inent forenqoloyinfglowfrequency currents in 'estajblishing- 'connection's either ona'rnanw' ali orionan automatic basis 'over said line circuits; anda'carrier current at audio frequency 4 for" transmitting? said lowfrequency currents over said lines; I

7 6." In atelephonesystem for handling-long distanc'e traffi'c, linesopaque tolow frequency currents; sources of'low frequency currents, a"source of high=frquency current, equip ment for rendering said lowfrequency currents effective in signal control for handling connectionson a manual basis over lines, means: for employingsaid low and saidhigh'frequer'fcy currents in establishing con nection'son anautomaticbasis' also Over said lines, -and-means for employing the highfrequency'current as 'a c'arrier agent for the low frequency currentsfor the signalingrelative v to said inanual connections and; also as acarrier agent for the low frequency currents when" they are required insaid automatic connections: 7 I

7'. In aitelephone distance traffic, a line circuit opaque ,to; lowfrequency currents, sources of low frequency current, a' source of;audio frequency carrier cur'r'en't for transmitting said loW' frequencycurrents over said line, -me,a1is for-employing said carrierfrequencyalone and also as a carrier ,forsaid-low frequency currentsQ'dlltlillling; respective OPGmtion's'm the" automaticestablishment ofconnections in a first direction over said line, and means to render.

signals effective in the opposite direction over said line circuit durmgper1ods signals may be under transmission in the first direction overthe same line circuit.

8. 1 In a telephone system for handling connections, a long line circuitsubstantially opaque to low frequency currents, sources of low frequencycurrent and audio frequency responsive to demodulated low frequencycurrents, and means jointly under control of said master relayand saidlow frequency relays for rendering said signaling current effective toautomatically extend a connection from said line circuit.

9. In a telephone system for establishing connections either on a manualor an automatic basis, a long line substantially opaque to currents atlow frequencies, a transmitting system comprising sourcesof lowfrequency currents and a source of audio frequency carrier current inwhich the phenomenon of modulation is established when said lowfrequency currents may be connected thereto,

a receiving system comprising demodulator means, rectifier means andrelays respectlvely responsive to rectified carrier current and todemodulated or low frequency currents, automatic switching means forextending a connection from said line, manual switching means includingsignals for manually extending connections from said line, and

means included with said transmitting system for selectively applyingsaid currents over said line in rendering the receiving equipmenteffective to establish an automatic connection or to control saidsignals of the manual switching means.

10. In a system for automatically establishing telephone connections, aline substantially opaque to currents of low frequency, a source ofvoice frequency alternating current at one end of said line, a source ofaudio frequency carrier current and a source of low frequency current atthe other end of said line, a receiving system comprising rectifiermeans, demodulator means, and relays respectively responsive to saidcarrier current and said low frequency current, an automatic switchingsystem undercontrol of said receiving system, means for applying saidcarrier current to said line in seizing and conditioning said automaticswitching system for the reception of selective impulses, means toautomatically apply an impulse formed of said carrier current modulatedby said'low frequency current over said line, and signal meanscontrolled by said opaque to direct currents and to low frequen-' cyalternating currents, a source of carrier current of audio frequency, asource of low frequencycurrents for modulating said carrier current, areceiving system for said modulated currents and said carrier current,automatic switching means controlled by said receiving system, andtransmitting meansfor selectively applyingsaid currents over said lineto respectively control said automatic equipment in the operations ofseizing, dialing and ringing inautomatically extending a connection fromsaid line.

12. In a telephone system, a calling and a. called station, a linecircuit opaque to direct current and to alternating currents of lowfrequency, an automatic switching system including a source of audiofrequency current and a low frequency modulating current therefor, meansfor controlling said switching system from said callingpoint in Iconnecting said line to said called station, a signal and control meanstherefor at said calling station, and means responsive on saidconnection being established to said called station to apply an impulseof said modulated current over said line to energizesaid signal. 13..Ina telephone system, a calling and a called station, a line circuitopaque to direct current and to alternating currents of low frequency, asignal and control means therefor at said calling station, an automaticswitching system including a source of audio frequency carrier currentand a source of low frequency current for modulating said carriercurrent, means for dialing over said line in controlling said switchingsystem to connect the line to the called station, and means responsiveduring the operation of said switchingsystem and following establishmentof a connection to apply a single impulse of said modulated current oversaid line at different times in controlling said signal to respectivelyindicate that dialing may be proceeded with, dialing has been completed,the co-nnectionhas been established with the called station, the called.station has responded and finally that the called station hasdisconnected.

14. In a telephone system, the combinalea terminating end fortransmitting to the I originating end signaling currents fromalternatlng current sources operat ng when the path being selected bythe automatic extension means is busy, a signal at the originating end,means at the originating end for operating said signal responsive I tosaid signaling currents incoming during the sending of dialing impulsesover the toll line.

15. In a telephone system, the combination of a toll linewith means forextending the line automatically, alternating current sources, means atthe originating end of the line for producing and transmitting dialingimpulses from a current source to control the automatic extension imeans comprising a pulsing circuit, a transformer, means for switchingthe toll line conductors to the secondary of the transformer and thepulsing circuit through the primary of the transformer when the pulsingdevice is operated, means at the terminating end for transmitting overthe toll line conductors to the originating end signaling current fromalternating current sources indicating that the path being selected isbusy, a signal at the originating end, and means at the originating endfor operating said signal responsive to said signaling currents incomingwhile the toll line conductors are closed through the secondaryof saidtransformer.

16. In a telephone system, the combination of a toll line with means forextending the line automatically, high frequency and low frequencyalternating current sources, means at the originating end of said linefor transmitting dialing impulses from an alternating current source forcontrolling the automatic extension means, means at the terminating endfor transmitting to the originating end signals comprising alternatingcurrent from a high frequency source modulated by alternating currentfrom a low frequency source operated when the path being selected by theautomatic extension means is busy, a signal at the originating end, andmeans at the originating end for the operation of said signal responsiveto the modulated signal incoming during the sending of dialing impulsesover the toll line. 7

17. In a telephone system, the combination of a toll line with means forextending the line automatically, high frequency and low frequencysources, means at the originating end of said line for transmittingdialing impulses for controlling the automatic extension means, anoperators telephone circuit connected to the originating end of theline, means for connecting the dialing means to the originating end ofthe line and disconnecting the operators telephone circuit from theline, a visual signal at the originating end, means at the terminatingend for transprising alternating current from a high frequency sourcemodulated by alternating cur- A rent from a low frequency sourceoperating when the path being selected by the automatic extension meansis busy, and means at the originating end responsive to said modulatedsignals for the operation of said visual signal when the dialing meansis operating and for operating the visual signal and for transmittingaudible indications to the operators telephone set when the dialingmeans is disconnected from the line.

18. A telephone system, including transmission circuits and a source ofmodulated alternating currents for signaling over said circuitscharacterized in this that said currents are produced by meanscomprising a source of direct current, a vibratory relay of thesh'ort-circuiting type connected to said source of direct current, sai'drelay provided. with an armature having a natural period of highfrequency for the production of'high frequency alternating current, anda vibratory relay of the same type connected to said direct currentsource and provided with an armature having a natural period of lowfrequency for the production of low frequency alternating current, and atransformer having a winding associated with each vibratory relay and athird or output winding for supplying said modulated currents to saidtransmission circuits.

19. In a telephone system, the combination of subscribers stations witha toll line terminating in means for extending the line au tomaticallyto a subscribers station, high frequency and low frequency alternatingcurrent sources, a supervisory signal at the originating end forindicating the progress of an automatic connection, means at theterminating end for transmitting to the originating end an impulse ofcurrent comprising alternating current from a high frequency sourcemodulated by alternating current from a low frequency source atintervals during the operation of the automatic extension means, andmeans at the originating end responsive to said impulses to actuate saidsignal on the receipt of thefirst impulse and to restore said signal toits normal condition upon the receipt of the second impulse andthereafter alternating operating and restoring the signal in response tosueceeding impulses.

In witness whereof, I hereunto subscribe my name this 13th day ofDecember, A. I). 1924;. Y

HENRYW. ONEILL.

